Reunion

Reunion is an auto-ability that has a chance to restore used orbs as prismatic orbs. Ability casts and element drives count towards usage.

Reunion and Prismatic Return share the same functionality, and work independently of each other.

Formula
Expected orbs refunded per cast = -(orb cost - orb return) + (reunion% × orb cost)

If the number is negative, then you are expected to eventually run out of orbs. If the number is positive, then you are expected to be able to keep using the ability without running out of orbs.